cc: Make LayerTreeHostImpl::SwapBuffers not virtual.

cc/test/test_hooks.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_TEST_TEST_HOOKS_H_
 #define CC_TEST_TEST_HOOKS_H_
 
 #include "base/macros.h"
 #include "cc/animation/animation_delegate.h"
 #include "cc/trees/layer_tree_host.h"
@@ skipping 28 matching lines @@
   virtual void CommitCompleteOnThread(LayerTreeHostImpl* host_impl) {}
   virtual void WillActivateTreeOnThread(LayerTreeHostImpl* host_impl) {}
   virtual void DidActivateTreeOnThread(LayerTreeHostImpl* host_impl) {}
   virtual void InitializedRendererOnThread(LayerTreeHostImpl* host_impl,
                                            bool success) {}
   virtual DrawResult PrepareToDrawOnThread(
       LayerTreeHostImpl* host_impl,
       LayerTreeHostImpl::FrameData* frame_data,
       DrawResult draw_result);
   virtual void DrawLayersOnThread(LayerTreeHostImpl* host_impl) {}
-  virtual void SwapBuffersOnThread(LayerTreeHostImpl* host_impl, bool result) {}
-  virtual void SwapBuffersCompleteOnThread(LayerTreeHostImpl* host_impl) {}
+  // Note that this is called asynchronously from the LayerTreeHostImpl
+  // performing its draw, so you should record state you want to use here
+  // in DrawLayersOnThread() instead. For that reason this method does not
+  // receive a LayerTreeHostImpl pointer.
+  virtual void SwapBuffersCompleteOnThread() {}
   virtual void NotifyReadyToActivateOnThread(LayerTreeHostImpl* host_impl) {}
   virtual void NotifyReadyToDrawOnThread(LayerTreeHostImpl* host_impl) {}
   virtual void NotifyAllTileTasksCompleted(LayerTreeHostImpl* host_impl) {}
   virtual void NotifyTileStateChangedOnThread(LayerTreeHostImpl* host_impl,
                                               const Tile* tile) {}
   virtual void AnimateLayers(LayerTreeHostImpl* host_impl,
                              base::TimeTicks monotonic_time) {}
   virtual void UpdateAnimationState(LayerTreeHostImpl* host_impl,
                                     bool has_unfinished_animation) {}
   virtual void WillAnimateLayers(LayerTreeHostImpl* host_impl,
@@ skipping 88 matching lines @@
       const proto::CompositorMessageToImpl& proto) {}
 
   // Used to notify the test to destroy the Remote client LayerTreeHost on
   // receiving a CompositorMessageToImpl of type CLOSE_IMPL.
   virtual void DestroyRemoteClientHost() {}
 };
 
 }  // namespace cc
 
 #endif  // CC_TEST_TEST_HOOKS_H_